Slow-Cooker Curried Cauliflower and Potatoes

Process the cilantro, crushed tomatoes, and 1 cup of the onions in a blender until smooth.

Melt the butter in a medium-sized nonstick skillet over medium. Add the remaining 1 cup onions, and stir to coat. Cover and cook until translucent, about 5 minutes. Add 1 1/2 tablespoons of the curry powder, and cook, stirring constantly, until fragrant, about 1 minute. Add the cilantro mixture to the skillet, and cook, stirring often, until bubbly, about 3 minutes.

Place the potatoes and cauliflower in a 5- to 6-quart slow cooker coated with cooking spray. Stir in the curry mixture. Cover and cook on LOW until the vegetables are tender, about 4 hours. Stir in the spinach, plum tomatoes, and salt. Top each serving with the sour cream. Sprinkle evenly with the additional curry powder, if desired.